SNBL USA is accused of letting its research primates, including dozens of macaque monkeys (like the one pictured), die on its watch.

A medical testing lab based in Washington State allowed nearly 40 primates to die through willful violations of basic treatment standards, according to a federal complaint.

The complaint filed by the U.S. Department of Agriculture accuses the SNBL USA lab of failing to meet “the minimum requirements” of the Animal Welfare Act — leading to the grisly deaths of 38 primates between 2011 and this year.

“The gravity of the violations alleged in this complaint is great,” the filing says, adding that the lab “failed to provide adequate veterinary care to animal and failed to meet the minimum standards for its facilities.”

SNBL USA is the American arm of the Japan-based Shin Nippon Biomedical Laboratories. The company says it has more than 40,000 animals under its watch, and that it used nearly 3,000 of them for research in 2015.

The company has previously violated the Animal Welfare Act, and paid for it — facing a $36,852 penalty in 2006 and a $12,937 penalty in 2009.

But the new complaint says the lab continued its callous treatment of primates for years, often allowing them to die through negligence or careless treatment.

The complaint details several alleged violations, with some leading the mass monkey deaths.

According to the complaint, one primate died from strangulation in 2010 after getting caught in a cable. Another died of suffocation in 2015 after the primate’s head got stuck in a cage.

Twenty-five macaque monkeys died in December 2013 after traveling from Cambodia to the lab’s American facilities; they did not receive veterinary care after showing signs of sickness and physical distress. Six macaques died this May during liver biopsy procedures from workers who were “inadequately trained," the filing says.

The complaint also says the labs kept primates in enclosures with mold, broken wires, rusted metal and sharp edges.

The company could face further fines and a potential loss of licenses if the violations are substantiated.

“We take these allegations seriously and are fully cooperating with the USDA to ensure that we are in complete compliance,” SNBL executive vice president Steven Glaza said in a statement to the Seattle Times.

“This is everyone’s priority.”

The USDA filed the complaint Sept. 26 but did not make it public until this month.